The present disclosure relates to infusion therapy with vascular access devices. Infusion therapy is one of the most common health care procedures. Hospitalized, home care, and other patients receive fluids, pharmaceuticals, and blood products via a vascular access device inserted into the vascular system. Infusion therapy may be used to treat an infection, provide anesthesia or analgesia, provide nutritional support, treat cancerous growths, maintain blood pressure and heart rhythm, or many other clinically significant uses.
Infusion therapy is facilitated by a vascular access device. The vascular access device may access a patient's peripheral or central vasculature. The vascular access device may be indwelling for short term (days), moderate term (weeks), or long term (months to years). The vascular access device may be used for continuous infusion therapy or for intermittent therapy.
A common vascular access device is a plastic catheter that is inserted into a patient's vein. The catheter length may vary from a few centimeters for peripheral access to many centimeters for central access. The catheter may be inserted transcutaneously or may be surgically implanted beneath the patient's skin. The catheter, or any other vascular access device attached thereto, may have a single lumen or multiple lumens for infusion of many fluids simultaneously.
Although several techniques for placing such catheters are practiced in the art, many generally include the step of inserting at least a portion of the needle into the target vessel and then sliding the catheter over the needle into place. The medical worker attempts to verify proper placement of the catheter within the blood vessel. Catheter and introducer needle assemblies have been provided that include means for verifying proper placement of the catheter in a blood vessel such as a flashback chamber in the catheter hub or a notch in the introducer needle.
Once placement of the needle has been confirmed by the observation of flash, the user may temporarily occlude flow in the blood vessel at the catheter tip, remove the needle, leaving the catheter in place, and attach a device to the catheter for fluid removal, input, or to seal the catheter. This process has been somewhat difficult in practice since many placement sites simply do not allow easy occlusion of the target vessel. Additionally, even when such occlusion is achieved, it may be imperfect, thus resulting in blood leaking from the catheter, endangering the medical personnel employing it.
Catheter and introducer needle assemblies have thus been provided in the art that provide a variety of seals or “septa” for preventing outflow of fluid during and following removal of the introducer needle. These structures are generally elastomeric plates designed to closely conform to the shape of a needle during storage and use to prevent leaking, then to seal upon removal of the needle. In an ideal vascular access device, the septum would continuously seal the patient's vascular system, which may include external vascular equipment intentionally coupled to the patient's internal vascular system by a medical practitioner, from the external environment.
As with most systems, one of the biggest challenges to the proper function of the vascular access device is when there is a change in the system, such as when different medical devices are connected or disconnected from the vascular access device. If the seal against the external environment is broken during the connection or disconnection of a medical device, there is the possibility of infection being introduced into the patient's vascular system. Additionally, if a pressure difference is created across the vascular access device, there becomes the possibility that blood will be drawn up the catheter system and possibly into the vascular access device or beyond. Alternatively, a pressure difference across the vascular access device may make it more difficult to couple other medical devices to the vascular access device.
Vascular access devices are often coupled with a blunted cannula, such as the tip of a syringe, with a male Luer connector, or with other medical devices. These medical devices may be coupled to the vascular access devices by pressing a portion of the medical device into a slit or passage in the septum. The tip penetrates the device deforming and separating at least portions of the two opposing slit surfaces of the septum. The septum and the slit may be configured to seal, or at least substantially seal, around the tip as it is inserted into the vascular access device. Accordingly, the surfaces near the slit ends may not be separated until the tip is sufficiently inserted into vascular access device. The tip serves to open the slit to allow fluid to pass through the device, into the catheter, and out the end of the catheter when the device is in use.
Repeated transitions of the septum between open and closed configurations apply stress to the septum. In some experiences the septum has been seen to tear, either slightly or more significantly, at the edges of the slit that allows other devices to access the internal vascular system through the lumen of the body. In previous vascular access devices, two common tear patterns have been observed: radial tearing and circumferential tearing. Depending on the nature of the tear, the impacts of the tear may include a decrease in the quality of the seal formed by the septum or pieces or particles of the septum breaking free from the remainder of the septum.
Some medical devices are coupled to the vascular access device through a twisting motion by which the body or other portion of the medical device is coupled to the body of the vascular access device and by which a portion of the medical device is disposed in the slit or passage of the septum. Other methods of coupling the vascular access device to one or more medical devices may be used as well.
Therefore the need exists for a more efficient method of valving in vascular access devices which allows for the valve to open and close automatically and provides a minimal fluid flow restriction hence better flush properties, with a low stress imparted on the septum.